Update with changes from microsoft/TypeScript#15277

Author: rbuckton

tslib.es6.js

@@ -139,18 +139,17 @@ export function __asyncGenerator(thisArg, _arguments, generator) {
     function verb(n) { return function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]), next(); }); }; }
     function next() { if (!c && q.length) resume((c = q.shift())[0], c[1]); }
     function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(c[3], e); } }
-    function step(r) { r.done ? settle(c[2], r) : Promise.resolve(r.value[1]).then(r.value[0] === "yield" ? _yield : r.value[0] === "delegate" ? delegate : fulfill, reject); }
-    function _yield(value) { settle(c[2], { value: value, done: false }); }
-    function delegate(r) { step(r.done ? r : { value: ["yield", r.value], done: false }); }
+    function step(r) { r.done ? settle(c[2], r) : Promise.resolve(r.value[1]).then(r.value[0] === "yield" ? send : fulfill, reject); }
+    function send(value) { settle(c[2], { value: value, done: false }); }
     function fulfill(value) { resume("next", value); }
     function reject(value) { resume("throw", value); }
     function settle(f, v) { c = void 0, f(v), next(); }
 };
 
 export function __asyncDelegator(o) {
-    var i = { next: verb("next"), "throw": verb("throw", function (e) { throw e; }), "return": verb("return", function (v) { return { value: v, done: true }; }) };
+    var i = { next: verb("next"), "throw": verb("throw", function (e) { throw e; }), "return": verb("return", function (v) { return { value: v, done: true }; }) }, p;
     return o = __asyncValues(o), i[Symbol.iterator] = function () { return this; }, i;
-    function verb(n, f) { return function (v) { return { value: ["delegate", (o[n] || f).call(o, v)], done: false }; }; }
+    function verb(n, f) { return function (v) { return v = p && n === "throw" ? f(v) : p && v.done ? v : { value: p ? ["yield", v.value] : ["await", (o[n] || f).call(o, v)], done: false }, p = !p, v; }; }
 };
 
 export function __asyncValues(o) {

tslib.js

@@ -169,18 +169,17 @@ var __asyncValues;
         function verb(n) { return function (v) { return new Promise(function (a, b) { q.push([n, v, a, b]), next(); }); }; }
         function next() { if (!c && q.length) resume((c = q.shift())[0], c[1]); }
         function resume(n, v) { try { step(g[n](v)); } catch (e) { settle(c[3], e); } }
-        function step(r) { r.done ? settle(c[2], r) : Promise.resolve(r.value[1]).then(r.value[0] === "yield" ? _yield : r.value[0] === "delegate" ? delegate : fulfill, reject); }
-        function _yield(value) { settle(c[2], { value: value, done: false }); }
-        function delegate(r) { step(r.done ? r : { value: ["yield", r.value], done: false }); }
+        function step(r) { r.done ? settle(c[2], r) : Promise.resolve(r.value[1]).then(r.value[0] === "yield" ? send : fulfill, reject); }
+        function send(value) { settle(c[2], { value: value, done: false }); }
         function fulfill(value) { resume("next", value); }
         function reject(value) { resume("throw", value); }
         function settle(f, v) { c = void 0, f(v), next(); }
     };
 
     __asyncDelegator = function (o) {
-        var i = { next: verb("next"), "throw": verb("throw", function (e) { throw e; }), "return": verb("return", function (v) { return { value: v, done: true }; }) };
+        var i = { next: verb("next"), "throw": verb("throw", function (e) { throw e; }), "return": verb("return", function (v) { return { value: v, done: true }; }) }, p;
         return o = __asyncValues(o), i[Symbol.iterator] = function () { return this; }, i;
-        function verb(n, f) { return function (v) { return { value: ["delegate", (o[n] || f).call(o, v)], done: false }; }; }
+        function verb(n, f) { return function (v) { return v = p && n === "throw" ? f(v) : p && v.done ? v : { value: p ? ["yield", v.value] : ["await", (o[n] || f).call(o, v)], done: false }, p = !p, v; }; }
     };
 
     __asyncValues = function (o) {